The RHS has concluded that nitrogen depletion is negligible.
I used chipped bark to great effect in my last garden for paths and as weed suppressant mulches. In this new garden I don't need paths but I have just ordered 10 cubic metres of the stuff for mulching new beds to keep weeds down and retain moisture.
Vendée - 20kms from Atlantic coast.
"The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
Hostafan - no criticism of you intended you clearly have found what works well for you, & I do not doubt its usefulness. Your woodchip is mixed with other materials, the grass clippings will supply the Nitrogen to aid the composting process- but you know that already I am sure.
You have rumbled me! I was a "Biomedical Scientist" in a former life. I was in the backroom with all the ones in white coats who were not Doctors.
If the RHS conclusion is that the depletion is negligible then I bow to their research.
The only true example of depletion I have seen was an extreme case where someone had a large heap of woodchip on their plot. When a new tenant came & cleared it the clay underneath was Blue, another plot holder who was even more nerdy than me, did a soil test on a sample and got a negative Nitrogen reading. I accept that this is only one example and not true research and most importantly the most avid mulcher would not put that depth of woodchip down. It does show that if you want to compost it properly then you have to do what Hostafan does & layer it with other soft high nitrogen material.
I think piling a huge heap of any organic matter on soil would have a detrimental effect if left long enough but the advice for mulching is a depth of just 2 or 3 inches which allows moisture and air, if not light, so the soil is hardly affected. I've always found mine to be full of worms and other critters and that plants grow well with reduced competition from weeds.
Vendée - 20kms from Atlantic coast.
"The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
Atmospheric nitrogen is biologically unavailable except to nitrogen-fixing bacteria (free-living or associated with certain plants such as legumes, alders, Gunnera). Woodchip mulch will primarily be broken down by wood-rotting fungi which will be taking nitrogen from the soil, not the air. So the soil will be depleted of nitrogen but its organic matter content will be improved in the long term. In any case I don't see how a small amount of nitrogen depletion would really be relevant for paths where you aren't growing any plants.
Regarding slugs the woodchip should also harbour predators such as centipedes and beetles, so I doubt it would cause much of a problem.
I agree I'd happily use woodchip mulch on paths - I'm hoping to get some free later this year to try on the paths between our vegetable beds (currently grass/weeds). I wasn't disagreeing with you in general.
Wood decay is generally fungal because it's high in carbon (cellulose and other molecules) but low in other nutrients such as nitrogen. Unlike single-celled bacteria, fungi have the advantage of being filamentous with a hyphal network extending over a large area so they can transport nutrients from the soil to enable them to break down the wood and utilise the stored energy (and vice versa they can use the energy from the wood to compete for and extract nutrients in the soil). Certain fungi also have the enzymes necessary to break down lignin.
Just finished watching 'Back to Eden' documentary. This guy uses wood chippings to mulch his veg and flower beds. He reckons wood chippings only take the nitrogen from the soil when it is actually dug into the beds. Mulching causes negligible depletion and is replaced once the chips have rotted.
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The RHS has concluded that nitrogen depletion is negligible.
I used chipped bark to great effect in my last garden for paths and as weed suppressant mulches. In this new garden I don't need paths but I have just ordered 10 cubic metres of the stuff for mulching new beds to keep weeds down and retain moisture.
Interesting stuff. I love a pedant too. I call it 'science'.
Hostafan - no criticism of you intended you clearly have found what works well for you, & I do not doubt its usefulness. Your woodchip is mixed with other materials, the grass clippings will supply the Nitrogen to aid the composting process- but you know that already I am sure.
Firefly give it a go I am sure it will be fine.
Iain, I know you weren't.
Firefly-
You have rumbled me! I was a "Biomedical Scientist" in a former life. I was in the backroom with all the ones in white coats who were not Doctors.
If the RHS conclusion is that the depletion is negligible then I bow to their research.
The only true example of depletion I have seen was an extreme case where someone had a large heap of woodchip on their plot. When a new tenant came & cleared it the clay underneath was Blue, another plot holder who was even more nerdy than me, did a soil test on a sample and got a negative Nitrogen reading. I accept that this is only one example and not true research and most importantly the most avid mulcher would not put that depth of woodchip down. It does show that if you want to compost it properly then you have to do what Hostafan does & layer it with other soft high nitrogen material.
I think piling a huge heap of any organic matter on soil would have a detrimental effect if left long enough but the advice for mulching is a depth of just 2 or 3 inches which allows moisture and air, if not light, so the soil is hardly affected. I've always found mine to be full of worms and other critters and that plants grow well with reduced competition from weeds.
Atmospheric nitrogen is biologically unavailable except to nitrogen-fixing bacteria (free-living or associated with certain plants such as legumes, alders, Gunnera). Woodchip mulch will primarily be broken down by wood-rotting fungi which will be taking nitrogen from the soil, not the air. So the soil will be depleted of nitrogen but its organic matter content will be improved in the long term. In any case I don't see how a small amount of nitrogen depletion would really be relevant for paths where you aren't growing any plants.
Regarding slugs the woodchip should also harbour predators such as centipedes and beetles, so I doubt it would cause much of a problem.
Ian says
it is the bacteria that break down wood chip that consumes the Nitrogen
Onopordum says
Woodchip mulch will primarily be broken down by wood-rotting fungi
I still maintian, whatever breaks it down, it's not going to do any harm to plants, and certainly none to paths, but others are free to disagree.
Last edited: 07 June 2017 13:06:19
I agree I'd happily use woodchip mulch on paths - I'm hoping to get some free later this year to try on the paths between our vegetable beds (currently grass/weeds). I wasn't disagreeing with you in general.
Wood decay is generally fungal because it's high in carbon (cellulose and other molecules) but low in other nutrients such as nitrogen. Unlike single-celled bacteria, fungi have the advantage of being filamentous with a hyphal network extending over a large area so they can transport nutrients from the soil to enable them to break down the wood and utilise the stored energy (and vice versa they can use the energy from the wood to compete for and extract nutrients in the soil). Certain fungi also have the enzymes necessary to break down lignin.
Just finished watching 'Back to Eden' documentary. This guy uses wood chippings to mulch his veg and flower beds. He reckons wood chippings only take the nitrogen from the soil when it is actually dug into the beds. Mulching causes negligible depletion and is replaced once the chips have rotted.